Drift diameter gauge and drift diameter gauge assembly

The utility model provides a drift diameter gauge and a drift diameter gauge assembly. The drift diameter gauge comprises a hollow drift diameter gauge body and at least two reducing assemblies. At least two mounting grooves are formed in the outer side surface of the drift diameter gauge body; the at least two mounting grooves are formed at intervals in the axial direction of the drift diameter gauge body; a reducing assembly is accommodated in each mounting groove; the reducing assembly comprises a movable piece and an elastic piece. The movable pieces are connected into the corresponding installation grooves through the elastic pieces, part of the structures of the movable pieces protrude out of the outer side face of the drift diameter gauge body under the action of elastic force of the elastic pieces, and the movable pieces can move towards the inner sides of the depth directions of the installation grooves when being subjected to acting force towards the inner sides of the driftdiameter gauges. The util